Formulation and characterization of high thermal conductivity copper nanofluids for a single step industrial heat transfer application system for microelectronics and automobiles

This research article investigate a novel method for the formulation of stable, non–agglomerated copper nanofluids by reducing copper sulphate pentahydrate with sodium hypophosphite chemical as a reducing agent in ethylene glycol as base power fluid by means of conventional heat transfer process in electronics, electrical and automobiles. This is an insitu, single step method, which gives very high yield of product with less time duration. The characterization of the nanofluid was done by particle size analyzer, x-ray diffraction (XRD), uv-visible (UV-VIS) analysis and Fourier transform infrared spectroscopy (FTIR) followed by thermal conductivity studies of nanofluid by the well known transient hot wire anemometer method

Direct Nitrate Reductase Assay versus Microscopic Observation Drug Susceptibility Test for Rapid Detection of MDR-TB in Uganda

The most common method for detection of drug resistant (DR) TB in resource-limited settings (RLSs) is indirect susceptibility testing on Lowenstein-Jensen medium (LJ) which is very time consuming with results available only after 2–3 months. Effective therapy of DR TB is therefore markedly delayed and patients can transmit resistant strains. Rapid and accurate tests suitable for RLSs in the diagnosis of DR TB are thus highly needed. In this study we compared two direct techniques - Nitrate Reductase Assay (NRA) and Microscopic Observation Drug Susceptibility (MODS) for rapid detection of MDR-TB in a high burden RLS. The sensitivity, specificity, and proportion of interpretable results were studied. Smear positive sputum was collected from 245 consecutive re-treatment TB patients attending a TB clinic in Kampala, Uganda. Samples were processed at the national reference laboratory and tested for susceptibility to rifampicin and isoniazid with direct NRA, direct MODS and the indirect LJ proportion method as reference. A total of 229 specimens were confirmed as M. tuberculosis, of these interpretable results were obtained in 217 (95%) with either the NRA or MODS. Sensitivity, specificity and kappa agreement for MDR-TB diagnosis was 97%, 98% and 0.93 with the NRA; and 87%, 95% and 0.78 with the MODS, respectively. The median time to results was 10, 7 and 64 days with NRA, MODS and the reference technique, respectively. The cost of laboratory supplies per sample was low, around 5 USD, for the rapid tests. The direct NRA and MODS offered rapid detection of resistance almost eight weeks earlier than with the reference method. In the study settings, the direct NRA was highly sensitive and specific. We consider it to have a strong potential for timely detection of MDR-TB in RLS

Phenotypic and Functional Characterization of Human Mammary Stem/Progenitor Cells in Long Term Culture

Background: Cancer stem cells exhibit close resemblance to normal stem cells in phenotype as well as function. Hence, studying normal stem cell behavior is important in understanding cancer pathogenesis. It has recently been shown that human breast stem cells can be enriched in suspension cultures as mammospheres. However, little is known about the behavior of these cells in long-term cultures. Since extensive self-renewal potential is the hallmark of stem cells, we undertook a detailed phenotypic and functional characterization of human mammospheres over long-term passages. Methodology: Single cell suspensions derived from human breast `organoids' were seeded in ultra low attachment plates in serum free media. Resulting primary mammospheres after a week (termed T1 mammospheres) were subjected to passaging every 7th day leading to the generation of T2, T3, and T4 mammospheres. Principal Findings: We show that primary mammospheres contain a distinct side-population (SP) that displays a CD24(low)/CD44(low) phenotype, but fails to generate mammospheres. Instead, the mammosphere-initiating potential rests within the CD44(high)/CD24(low) cells, in keeping with the phenotype of breast cancer-initiating cells. In serial sphere formation assays we find that even though primary (T1) mammospheres show telomerase activity and fourth passage T4 spheres contain label-retaining cells, they fail to initiate new mammospheres beyond T5. With increasing passages, mammospheres showed an increase in smaller sized spheres, reduction in proliferation potential and sphere forming efficiency, and increased differentiation towards the myoepithelial lineage. Significantly, staining for senescence-associated beta-galactosidase activity revealed a dramatic increase in the number of senescent cells with passage, which might in part explain the inability to continuously generate mammospheres in culture. Conclusions: Thus, the self-renewal potential of human breast stem cells is exhausted within five in vitro passages of mammospheres, suggesting the need for further improvisation in culture conditions for their long-term maintenance

Automated generation of the commutator algebra for NMR problems

A computer program has been developed for the automated generation of the Lie algebra of any general spin Hamiltonian. The program is written for Spin&#189; particles in FORTRAN-IV language. Application of this program is reported to the problem of five-spin systems (AX, and A<SUB>2</SUB>X<SUB>3</SUB>) evolving under collective modes

Studies on dissolution of magnetite in tetrafluoboric acid solution

341-342Dissolution kinetics of defect magnetite of compostion Fe2.84O4 in commercial fluoboric acid (HBF4) show a first order kinetic behaviour at 300 and 353K. The efficacy of regeneration of HBF 4 has been studied by ion-exchange using model mixtures of Fe3+ + HBF4 as well as solutions generated by dissolution of magnetite in HBF4. These data help in establishing the suitable chemistry conditions for possible regeneration of HBF4

Synthesis and Mechanical Studies on Reinforced Nanoclay with Ethylene Propylene-diene in PVP/PI Blended Polymers for Fluid Transport Structures and Non-conducting Electronic Insulator Geometries

A modified and reinforced hardened polymer of tris (2-methoxyethoxy) vinylsilane grafted ethylene-propylene-diene terpolymer (EPDM-g-TMEVS) has been prepared by bonding of tris (2-methoxyethoxy) vinylsilane onto ethylene propylene diene monomer (EPDM) by using dicumylperoxide (DCP) initiator. The linear blends based on EPDM-g-TMEVS have been synthesized with varying weight percentages of poly vinyl pyrrolidone and aromatic polyimide PVP/PI blends by melt and mixing process in a twin-screw extrude technique. Inthe same and similar manner, the dynamically sulfur based vulcanized and nanoclay reinforced blends of EPDM-g-TMEVS/PVP/PI have also been developed by using DCP and organically modified montmorillonite/china clay material by means of a twin-screw extruder. The grafting of TMEVS onto EPDM at bonding position present in the third monomer ethyledine norbornene (ENB) has been confirmed by Fourier Transform Infrared Spectroscopy (FTIR). The values of impact strength, percentage elongation at break, tensilestrength, flexural strength, flexural modulus and hardness are increased with an increase in the concentration of nanoclay particle due to efficient interaction between clay and blend constituents with interaction of polymer molecules into interlayer clay space. The structures made up of by these hardened composite polymeric materials are having high potential to withstand higher pressure, thermal shock and mechanical stress

Synthesis & IR & NMR Spectral Studies on Some Triorganotin(IV) Compounds Containing 2-Pyridylcarbinols

427-42

Analysis of collective modes in some A<SUB>M</SUB>X<SUB>N</SUB> systems

The behavior of spin&#189; AX3 and A2X2 systems evolving under cross-polarization (CP) and isotropic mixing (IM) is analyzed in detail by computing the time development of the density operator by commutator algebra. The two mixing processes are compared in these cases with respect to their coherence-transfer frequencies, efficiency, and the resulting multiplet patterns. The effect of two types of purge on the density operator is evaluated for the heteronuclear situation. spin&#189; AXN systems (N = 1, 2,.., 6) evolving under isotropic mixing are also analyzed employing zero-quantum-frame techniques. Several general properties of isotropic mixing are derived which contrast with the corresponding cross-polarization results. Explicit expressions are given for the X-coupled and gX-decoupled A signal as a function of the isotropic mixing period. The effect of two different purge procedures is evaluated for the heteronuclear case, and general conclusions are drawn about the intensity and time development of the multiplet components in CP and IM. The IM results, except for the discussion of purging, are directly applicable to experiments involving homonuclear spin-locking as well